The 3,000 Mile Autumn Journey of a Monarch Butterfly

Later this autumn, Canada geese honking overhead in majestic V-formations will be a dramatic reminder that many animals are conducting their fall migration. A subtler, but no less dramatic, migration will be that of the monarch butterfly, which is already underway.

The monarch (Danaus plexippus) migrate farther than any other butterfly in the world, covering distances up to 3,000 miles. Monarchs that emerge from their pupae in late summer and early fall will migrate south for the winter, roosting by the thousands in the mature forests of central Mexico. In the spring, these monarchs will mate and begin flying north. These northbound monarchs will perish on their journey, but not before laying the eggs of the next generation. Thus, their offspring will continue the cycle.

An unsolved mystery is how monarchs find the overwintering sites. The monarchs that reach Mexico have never been there. They are the great great grandchildren of the butterflies that were in Mexico the previous spring.

The Monarch Watch program, based at the University of Kansas, is a collaborative network of students, teachers, volunteers and researchers dedicated to the study of the monarch butterfly. Through the program, participants affix small round polypropylene “tags” to the wings of monarchs. A unique identification number and the address of the University of Kansas are imprinted on each tag. Each year many butterflies tagged in western Pennsylvania are found in Mexico.

Much remains unknown about the migration. It was not until 1976 that the overwintering grounds in Mexico were discovered. The Monarch Watch program helps researchers gain valuable information about the movement and life cycle of Danaus plexippus.

So as the fall asters, Joe-Pye weed and goldenrod bloom, look for monarchs stopping to sip nectar. As you enjoy their beauty, take a moment to consider the amazing journey that lies ahead of them.

Photo of tagged monarch butterfly provided courtesy of Monarch Watch.

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